In the beverage industry, the espresso process involves forcing hot water or steam under pressure through a particulate substance. The general method of making espresso coffee is well known. It involves the process or method of forcing hot water or steam through conventional coffee grounds or some extra fine coffee grounds. This method for making coffee differs significantly from the common methods for making drip-type or percolation coffees. The espresso coffee may be brewed with a mixture of espresso coffee grounds and cinnamon or other flavored syrups such as almond, orange, hazelnut, chocolate and the like. Espresso coffee generally is a dark full-bodied brew and may also be served as cappucino, caffe latte, caffe Americano, doppio, or macchiato.
Microwave ovens are widely used and known for a variety of heating tasks, including the heating of water for instant beverages or heating other beverages and foods. In addition, several devices have been proposed for brewing coffee in microwave ovens.
U.S. Pat. No. 4,104,957 issued Aug. 8, 1978 (Freedman et. al.) discloses a coffee brewing appliance comprising a carafe, a filter that fits in the neck of the carafe, and a water reservoir located over the filter. The water reservoir communicates with the filter by way of a thermally-controlled valve. When water in the water reservoir is heated by microwave radiation, the valve opens, allowing the water to flow into the filter, extracting coffee constituents from coffee grounds in the filter, so that a coffee beverage accumulates in the carafe.
U.S. Pat. No. 4,577,080 issued Mar. 18, 1986 (Grossman) discloses an appliance similar to that of Freedman et. al., except that instead of using a thermally-controlled valve to prevent cold water from the water reservoir from contacting coffee grounds in a filter, a body of non-toxic wax melts when the water reaches the desired temperature.
U.S. Pat. No. 4,721,835 issued Jan. 26, 1988 (Welker) discloses a device for brewing coffee in a microwave oven. The device comprises a jug having a top configured as a filter. Water and coffee grounds are placed in the jug, and the filter is fitted in the mouth of the jug. When the coffee has brewed, it can be poured from the jug, while the coffee grounds are retained by the filter.
U.S. Pat. No. 4,386,109 issued May 31, 1983 (Bowen et. al.) discloses an espresso coffee maker for use in a microwave oven. The water is stored in a microwave transparent reservoir which is adjacent to an aluminum pot. The pot and reservoir are coupled in a fixed spatial relationship by a collar. The collar includes a strainer which presses against a layer of coffee grounds when the collar is secured to the reservoir. The compressed coffee grounds in combination with the strainer for a pressure resistant seal over the opening of the reservoir. The water in the reservoir is heated by microwave energy. The pressure rises to a level sufficient to force steam and water in a downward direction through the coffee grounds into the pot, which stores the espresso coffee.
U.S. Pat. No. 4,381,696 issued May 3, 1983 (Koral) discloses a coffee brewing appliance that is generally similar to that disclosed by Freedman et. al.
U.S. Pat. No. 4,345,512 issued Aug. 24, 1982 (Moore) discloses a tea infuser for use in a microwave oven. The tea infuser, instead of being made of metal, is made of microwave-transparent plastic material.
U.S. Pat. No. 5,012,059 issued Apr. 30, 1991 (Boatman) discloses a device for heating water in a microwave oven. In Boatman's device, water is heated in a water reservoir, then forced from the water reservoir through a tube into a heating chamber, where it is further heated prior to draining through a filter filled with coffee grounds.
U.S. Pat. No. 4,990,734 issued Feb. 5, 1991 (Hirsch et. al.) discloses a method of preparing coffee where a mixture of water and coffee grounds is heated with microwave radiation, whereby a pressure gradient is produced across a filter, forcing filtrate into a vessel.
German No. OS 3,206,803 includes, seated one on the other, a coffee pot, a filter to receive coffee, and a water container. The water container is pervious to microwave radiation and the filter is developed so that substantially no liquid can pass through the filter under atmospheric or ambient pressure. The device is placed in a microwave oven in which the microwave radiation brings the water in the water container to a boil, while the coffee remains screened off. The formation of steam develops such a high pressure in the water container (up to 3.45 bar) that the water is forced through the filter.